1. Field of the Invention
The present invention relates to a semiconductor memory device. For example, the present invention relates to a semiconductor memory including MOS transistors each having a floating gate and a control gate.
2. Description of the Related Art
NOR type flash memories and NAND type flash memories are conventionally known as nonvolatile semiconductor memories and are commonly used. In recent years, a flash memory (referred to as a 2Tr flash memory below) has been proposed which has the advantages of both a NOR type flash memory and a NAND type flash memory. The 2Tr flash memory is disclosed in, for example, Wei-Hua Liu, “A2-Transistor Source-select (2TS) Flash EEPROM for 1.8V-Only Application”, Non-Volatile Semiconductor Memory Workshop 4.1, 1997.
In the flash memory, in operation, a row, decoder selects a word line connected to any of the memory cells arranged in a matrix. For example, Jpn. Pat. Appln. KOKAI Publication No. 2000-49312 makes various proposals for the configuration of the row decoder. However, the conventional row decoder has a large size, thus hindering a reduction in the size of the flash memory.